Personal “in-ear” monitoring systems are utilized by musicians, recording studio engineers, and live sound engineers to monitor performances on stage and in the recording studio. In-ear systems deliver a music mix directly to the musician's or engineer's ears without competing with other stage or studio sounds. These systems provide the musician or engineer with increased control over the balance and volume of instruments and tracks, and serve to protect the musician's or engineer's hearing through better sound quality at a lower volume setting. In-ear monitoring systems offer an improved alternative to conventional floor wedges or speakers, and in turn, have significantly changed the way musicians and sound engineers work on stage and in the studio.
Moreover, many consumers desire high quality audio sound, whether they are listening to music, DVD soundtracks, podcasts, or mobile telephone conversations. Users may desire small earphones that effectively block background ambient sounds from the user's outside environment.
Hearing aids, in-ear systems, and consumer listening devices typically utilize earphones that are engaged at least partially inside of the ear of the listener. Typical earphones have one or more drivers or balanced armatures mounted within a housing. Typically, sound is conveyed from the output of the driver(s) through a cylindrical sound port or a nozzle.
FIGS. 1A and 1B show a prior-art balanced armature driver 10 used in hearing aids, in-ear monitors (“IEMs”), audiometric tools, and consumer earphones. A metal case 12 (for example, mu-metal) is used for shielding the motor 50, the paddle 52, and the diaphragm support 54 of the armature. A top cup or lid 14 and a bottom cup or can 16 together form the metal case 12. In applications seen in the art, a sound entry tube 18 must attach to a secondary or multiple outlet paths (ultimately to get to the ear) without any acoustic leaks. Acoustic leaks cause the sound quality to degrade, especially at low frequencies. The methods of sealing the sound entry tube to the secondary outlet paths are typically accomplished using tubes, elastomeric molds, adhesives, Poron (compressible visco-elastic reticulated foam), or combinations thereof.
Additionally, the bottom cup or can 16 acts as the base part of the assembly such that all above components are built into it. Although this is a feasible manufacturing method and may be used in conjunction with the present disclosure, there is less “open processing surface” or area to assemble the components for this type of base part (a box with an open top). Having an “open processing surface” makes line of sight checking of fit and alignment of mating features via human eye or camera more feasible.
A prior art earphone assembly 100 is shown in FIG. 2. A first cover portion 102A and a second cover portion 102B form a housing for the internal components of the earphone. The housing contains a first balanced armature driver 104A and a second balanced armature driver 104B, a nozzle 112, and a coupling 118 for receiving a cable 116. The nozzle 112 mates with a sleeve 114, which is inserted into a user's ear. The cable 116 sends an audio signal to the drivers 104A, 104B, which create sound and output the sound into the nozzle 112. The nozzle 112 projects the sound directly into a user's ear canal.
The balanced armature drivers 104A, 104B are held in place inside the first cover portion 102A and the second cover portion 102B by a set of ribs 106 located on the second cover portion 102B, a Poron seal 110, and a molded thermoplastic elastomer (“TPE”) seal 108. The ribs 106 act to press the drivers 104A, 104B up against the Poron seal 110 and the TPE seal 108. The Poron seal 110 and the TPE seal 108 provide an acoustic seal between the nozzle 112 and the drivers 104A, 104B.